Modified versions of the classic A-frame tent or tarp shelter are known, and include both floored and floorless styles. Modern shelters of this type commonly use a weatherproof nylon or polyester fabric “fly” (canopy) supported by two spaced upright poles, for example adjustable length hiking or “trekking” poles. The main body of the canopy defines a lengthwise, generally rectangular main floor plan or “footprint” between the poles, under which hikers can shelter and sleep, with semi-pyramidal vestibule end portions of the canopy staked down outwardly of the poles. One or both of the vestibule ends usually includes a door. The canopy may be used alone as a floorless shelter, or in combination with an attached floor or inner tent made from varying fabrics.
Two poles erected at the peak ends of the canopy ridgeline support the ridgeline, while ground-level edges of the canopy are secured to the ground directly or through guy lines, using stakes or other fixed supports. The walls of the canopy generally slope directly toward the ground from the ridgeline and peaks, without vertical wall portions, and thus limit the interior useable space. Increasing the pole height and canopy slope angle for a given footprint increases useable space relative to the footprint, but can reduce the shelter's stability in wind and increase its weight. Generally available trekking poles limit practical maximum height to 145 cm/57 in or lower, absent separate trekking pole tip extenders.
As a practical matter, useable space is space where the canopy walls are high enough above the ground so that the occupants and their gear are not pressing against or distorting the canopy walls while inside. Although preferences will vary, I prefer to define useable space as the interior volume where all canopy fabric is 12″ (inches) or more above the ground. This allows room for feet and heads to be clear of the canopy fabric while sleeping.